Study Questions:

Methods:

This single-center, retrospective, cross-sectional study was conducted to examine the association between SDB and exercise testing outcomes independent of body mass index (BMI) and other cardiopulmonary risk factors. Between January 1, 2005 and January 1, 2010, 1,424 adults underwent exercise testing and within 6 months before first-time diagnostic polysomnography. Most subjects were referred for an exercise test for the evaluation of fatigue, chest pain, or palpitations. Exclusions included those with complex heart, lung, or kidney disease. Subjects with known coronary disease were not excluded. Subjects were categorized by apnea-hypopnea index (AHI) into four groups: <5, 5-14, 15-29, and >30. A logistic regression model incorporated age, gender, BMI, smoking, hypertension, diabetes, beta-blocker use, and cardiac and pulmonary disease as covariates. The primary variable of interest was functional aerobic capacity (FAC), which was calculated based on a nomogram using age, sex, baseline activity, and observed duration of exercise.

Conclusions:

The authors concluded that SDB severity was associated with reduced FAC and increased resting and peak DBP. Even after accounting for confounders, severe SDB was associated with attenuated FAC; impaired heart rate recovery; and higher resting, peak, and postexercise DBP.

Perspective:

This is the largest study to date to explore the relationship between untreated SDB and decreased exercise capacity. The cohort contained a small number of subjects with baseline smoking, pulmonary, or structural heart disease. Pulmonary function data were not available in all subjects. Several possible mechanisms by which SDB may lead to abnormalities in exercise capacity include: hypoxia, hypertension, arrhythmias, impaired muscle metabolism, and deconditioning due to poor sleep hygiene. Since this was a referral cohort population to an exercise laboratory, findings here may not apply to all patients with SDB.